Adjustable coolant pump

ABSTRACT

The invention is based on the task of developing an adjustable coolant pump driven by the engine, which pump does not require any outside energy for pressure and/or volume stream regulation, guarantees great failure safety, and is supposed to guarantee optimal warm-up of engines having great engine outputs relative to the displacement, which require coolant pumps having a very large design. 
     The adjustable coolant pump according to the invention, having an impeller disposed in torque-proof manner on a pump shaft, having a ring piston spring-loaded by a return spring, axially guided in a pump housing, on which piston a control slide valve disposed in the pump interior is rigidly attached, and which is characterized in that the ring piston and a filter sleeve provided with laser bores, together with other components, form a spring pressure space in the form of a ring cylinder in the interior of the coolant pump, which chamber is connected with a pressure chamber disposed on the pump shaft side, in such a manner that the valve piston of the pilot valve closes off a shaft bore disposed centrally in the pump shaft, which bore opens into the pressure chamber by way of transverse bores disposed in the pump shaft.

The invention relates to an adjustable coolant pump, particularly foruse in internal combustion engines.

Within the scope of the optimization of internal combustion engines,these have a tendency toward constantly greater engine outputs, whilethe displacement remains the same or often becomes smaller.

It is compulsory that the cooling output of the coolant pumps must beadapted to these greater engine outputs, so that in the case of engineshaving an increasing engine output, the related coolant pump mustalready summon up a correspondingly great conveying output in the lowerspeed of rotation range, and must be dimensioned to he correspondinglylarge, and this necessarily requires an increased space requirement inthe engine compartment. However, in order to not have the conveyingpressure generated by the coolant pump increase so greatly with anincreasing speed of rotation that as a consequence of a pressure buildupthat results in the coolant system of the internal combustion engine,modules such as heat exchangers, for example, are destroyed, the mostvaried pressure regulation functions are used. However, their use inturn requires a further demand for space in the engine compartment, andfurthermore often requires auxiliary energies for activation, whichenergies roust be made available by way of supply lines, which requirean even greater demand for space.

Thus, in the state of the art, overpressure protection is implemented byway of bypass lines, for example, wherein such solutions necessarilyresult in great energy losses.

A further possibility for implementing a pressure regulation functionwas previously described in DE 881 306 B. This is a centrifugal pumphaving a hydraulically activated control slide valve. The conveyingpressure of the pump is used as the activation pressure. A spring causesthe slide valve to be closed in the normal position/starting position.

In this solution, the displacement piston has a conveying pressureapplied to it on both sides. When needed, the spring space can berelieved of pressure by way of an external valve, thereby initiating anadjustment of the control slide valve in the “open” direction.

Because of the required inner and outer guide of the slide valve, thisembodiment requires very cost-intensive, complex production, andfurthermore an external control valve as well as externally conducteddrain lines, so that this design requires a great demand forspace/construction space. A further significant disadvantage of thedesign previously described in DE 881 306 B consists in that thissolution cannot guarantee the failure safety (fail-safe) that isabsolutely required for coolant pumps, because the conveying volumestream is completely closed off if the regulation device fails.Furthermore, in this design, the displacement piston sealing surfacesare also not protected against particles entrained by the conveyingmedium, on the one hand, and on the other hand, the shaft seal issubject to the stress of the full conveying pressure, so that not onlythe useful lifetime but also the reliability of the pump is greatlyrestricted.

Furthermore, the applicant presented a coolant pump having a pressureregulation function by means of a valve slide valve, which has provenitself in practice in the meantime, in EP 1657446 A2, in which pump thisvalve slide valve is adjusted by a central working piston disposedaround the pump shaft, against which piston a return spring that isdisposed around the pump shaft and adjusts/resets the valve slide valveinto the “fully open” starting position rests.

In this design, the impeller is furthermore mounted on the shaft inaxially displaceable but torque-proof manner. The conveying pressureacts between the pressure slant in the housing and the open impeller,and displaces the impeller counter to the spring force of a plate springthat lies against the rear side of the impeller when a preset value hasbeen reached. The conveying pressure of the pump decreases as a resultof the sealing gap relative to the pressure slant becoming larger duringthis axial displacement of the impeller. A prerequisite for this is thata space (i.e. the spring space) having a lower pressure level ascompared with the conveying pressure is present on the rear side of theimpeller.

However, in this solution, too, the coolant pump requires a relativelylarge construction space as a consequence of the control unit that canbe controlled externally with outside energy, the magnetic coil.

The setting element/spring element that “makes do” without outsideenergy in this solution, and has a pressure regulation function, is aplate spring used due to limitations of the construction space, whichspring is very greatly restricted in terms of its force/lift ratio, sothat the opening pressure can be adjusted only very imprecisely withthis solution.

A further solution of a design of a coolant pump having a pressureregulation function, here once again with a control slide valve, whichdesign has also proven itself in practice in the meantime, was presentedby the applicant in DE 10 2008 026 218 B4 and also in WO 2009/143832 A2.In this solution, the control slide valve is disposed on an aspring-loaded, axially displaceable ring piston, wherein the controlpressure for activation of the control slide valve is generated by anaxial piston pump that lies against the rear wall of the pump wheel,which wall is specifically configured as a slanted disk for thispurpose, and adjusted by means of a solenoid valve disposed in the pumphousing.

As the result of the use of the axial piston pump, this solution onceagain requires an increased demand for space in the engine compartment,as well as, furthermore, also in connection with the use of the solenoidvalve, once again outside energy with the related supply lines.

In the prior art, the applicant furthermore presented a further solutionthat has also proven itself in practice in the meantime, in DE 10 2008022 354 A1, which also allows active control of the conveying volumestream by means of a valve slide valve spring-loaded by a return spring,having a rear wall and an outer cylinder that is disposed on this rearwall and variably covers the outflow region of the impeller.

In the solution according to DE 10 2008 022 354 A1, the requiredhydraulic pressure that brings about the displacement of thespring-loaded valve slide valve, counter to the spring force of thereturn spring, is generated and, at the same time, adjusted by means ofan electromagnetically activated, special axial pump disposed on theoutside of the pump housing.

A further solution is known from DE 10 2012 207 387 A1, by means ofwhich a valve slide valve spring-loaded by a return spring, once againhaving a rear wall and an outer cylinder disposed on this rear wall andvariable covering the outflow region of the impeller, can behydraulically adjusted by means of a 3/2-way valve, wherein thehydraulic pressure required for adjustment of the slide valve isgenerated by a “second” impeller disposed on the pump shaft of theimpeller, of a further secondary pump integrated into the housing.

The invention is therefore based on the task of developing an infinitelyadjustable coolant pump (having a control slide valve), driven by way ofan drive wheel, which avoids all the disadvantages of the state of theart mentioned above, furthermore demonstrates clear energy advantages ascompared with constant pumps having an overpressure valve, particularlydoes not require any outside energy (such as hydraulics, vacuum,electrical energy) for pressure or volume stream regulation, guaranteesgreat failure safety (fail-safe), and is supposed to guarantee optimalheating of engines having great engine outputs with reference to thedisplacement, which require coolant pumps having a large design, and issupposed to influence the engine temperature during long-term operation,in infinite manner, in highly dynamic manner, and very reliably, oververy long periods of use, in very precise manner, and, in this regard,at the same time, is supposed to have a minimal construction size thatoptimally utilizes the construction space present in the enginecompartment, wherein the coolant pump to be developed is furthermoresupposed to be able to be produced in simple and cost-advantageousmanner, in terms of production and installation technology, and issupposed to constantly guarantee great operational safety and greatreliability over the entire useful lifetime.

According to the invention, this task is accomplished by an adjustablecoolant pump driven by way of a drive wheel, for internal combustionengines, in accordance with the characteristics of the independent claimof the invention.

Advantageous embodiments, details, and characteristics of the inventionare evident from the dependent claims as well as from the followingdescription of the solution according to the invention, in connectionwith four representations of the solution according to the invention.

The figures show:

FIG. 1: the adjustable coolant pump according to the invention, disposedon an engine housing 37, in a side view, in section;

FIG. 2: the pump shaft 4 with the pilot valve 20 in a spatial explodedrepresentation;

FIG. 3: the detail Z from FIG. 1 with a schematic representation of the“control streams” during the “opening phase” of the control slide valve12;

FIG. 4: the detail Z from FIG. 1 with a schematic representation of the“control streams” during the “closing phase” of the control slide valve12.

FIG. 1 shows the adjustable coolant pump according to the invention,disposed on an engine housing 37, having a pump housing 1, a pump shaft4 mounted on the pump housing 1 in a pump bearing 2, driven by a drivewheel 3, here in the design of a pulley 40, having an impeller 5disposed in torque-proof manner on a free, flow-side end of this pumpshaft 4, and having a ring piston 7 spring-loaded by a return spring 6,axially guided in the pump housing 1, on which piston the rear wall 8 ofa control slide valve 12 disposed in the pump interior 9 and having anouter cylinder 11 that variably covers the outflow region 10 of theimpeller 5 is rigidly attached, wherein a shaft seal 14 is disposed in aseal accommodation 13, between the pump shaft 4 and the pump housing 1,and furthermore, pump mandrels 15 formed by the pump housing 1 ordisposed on the pump housing 1 are disposed in the pump interior 9, onwhich mandrels a wall disk 16 positioned in a fixed position in the pumpinterior 9, between the impeller 5 and the rear wall 8 of the controlslide valve 12, is disposed.

It is essential to the invention that a slide valve guide 17 for thering piston 7 spring-loaded by the return spring 6 is disposed on thepump housing 1, which guide guides the ring piston 7 on the outer mantleand, at the same time, is furthermore at a free distance from the pumpshaft 4 with its inner mantle.

It is furthermore characteristic that the slide valve guide 17 liesagainst the wall disk 16 with its free, flow-side end, so that thecomponents that are adjacent to one another, i.e. the slide valve guide17, the wall disk 16, a sealing disk 33 disposed on the innercircumference of the disk, spaced apart from the pump shaft 4 by athrottle gap, radially movable on the wall disk 16, the pump shaft 4,and the shaft seal 14, jointly enclose/form a pressure chamber 18 in theform of a ring cylinder.

The sealing disk 33, disposed in the wall disk 16 in radially movablemanner, the inside diameter of which has only little play (tight runningseat) relative to the outside diameter of the pump shaft 4, represents athrottle gap that permits only slight leakages into the pressure chamber18.

In this regard, it is guaranteed by the placement of the shaft seal ring14 in the pressure chamber 18, according to the invention, in connectionwith the entire pump structure according to the invention, that theshaft seal ring 14 is protected against impermissibly high pressuresunder all operating conditions, and thereby a long useful lifetime ofthe shaft seal ring 14 is guaranteed, at great reliability.

It is also essential, in this regard, that one/multiple passage bore(s)19 is/are disposed in the slide valve guide 17, at a distance from thewall disk 16.

It is furthermore essential to the invention that a pilot valve 20consisting of a setting screw 22 provided with a central outlet bore 21,a valve spring 23, and a valve piston 24 are disposed in a valve seatbore at the impeller-side free end of the pump shaft 4, in such a mannerthat the valve piston 24 closes off a shaft bore 25 that opens into thevalve seat bore, disposed centrally in the pump shaft 4, in the closedstate of the pilot valve 20, which shaft bore opens into the pressurechamber 18 by way of one/multiple transverse bore(s) 26 disposed in thepump shaft 4. To clarify the structure, the pilot valve 20, the pumpshaft 4 having the pilot shaft 20 are shown in a spatial explodedrepresentation in FIG. 2.

It is also characteristic, however, that the return spring 6, which liesagainst the ring piston 7 with one spring end, lies against the springcontact 27 of a filter sleeve 29 provided with laser bores 28 with itsother spring end, and presses the sleeve against the wall disk 16 inthis regard, forming a seal.

The laser bores 28 prevent the entry of any dirt load and therebyincrease the reliability of the control apparatus according to theinvention. At the same time, the laser bores 28 in the arrangementaccording to the invention serve as an inflow aperture and guaranteethat the amount of liquid flowing in is not more than can drain away byway of the pilot valve 20.

In this regard, however, it is also essential to the invention that afilter piston slide valve 30 is rigidly disposed on the ring piston 7,which valve slides along the outside circumference of the filter sleeve29 when the ring piston 7 is displaced, and thereby frees the filtersleeve 29 of any dirt load, i.e. cleans the laser bores 28/(filterbores) disposed in the filter sleeve 29 of the dirt particleaccumulations in their inflow region, and thereby guarantees greatreliability, even under extreme conditions of use. It is furthermorecharacteristic that the ring piston 7, together with the filter pistonslide valve 30, the filter sleeve 29, the wall disk 16, and the slidevalve guide 17 enclose a spring pressure space 31 in the form of a ringcylinder.

It is also essential that a control slide valve seal 32 is disposed onthe outside circumference of the wall disk 16, i.e. toward the outercylinder 11, and the sealing disk 33 is disposed on the insidecircumference of the wall disk 16, and as a result, an impeller rearside space 34 disposed in the pump interior 9, between the pump shaft 4,the rear wall of the impeller 5, the wall disk 16, and the outercylinder 11 is separated, on the pressure side, from a control slidevalve interior 36 disposed between the rear wall 8, the filter sleeve29, the wall disk 16, and the outer cylinder 11, wherein the workingpressure that is built up in the spiral channel 39 is constantly appliedin the control slide valve interior 36, in that mandrel passages 35 aredisposed in the rear wall 8.

Now that the solution according to the invention has been explained, interms of its structure, using FIGS. 1 and 2, the method offunctioning/method of action of the coolant pump according to theinvention, the structure of which has been explained, will now bediscussed using FIGS. 3 and 4.

FIG. 3 shows the detail Z from FIG. 1 with a schematic representation ofthe “control streams” during the “opening phase” of the control slidevalve 12. In this movement direction of the control slide valve 12,referred to as the “opening phase” (represented in FIG. 3 with adirectional arrow R on the control slide valve 12), the control slidevalve 12 moves in the direction of the pulley 40 and, in this regard,opens the outflow region 10 of the impeller 5 with its outer cylinder11.

With an increasing speed of rotation of the pump shaft 4, the speed ofrotation of the impeller 5 increases, and thereby the working pressureincreases, i.e. the pressure in the spiral channel 39. This workingpressure builds up in the entire interior of the coolant pump accordingto the invention, which interior is not sealed off in any special way.

In this regard, a lower pressure, as compared with the working pressure,is applied to the impeller rear side space 34 (which is sealed offrelative to the control slide valve interior 36) and to the springpressure space 31 (which is connected with the control slide valveinterior 36 by way of the filter sleeve 29, provided with laser bores,which acts as a throttle).

Because the spring pressure space 31 is connected with the pressurechamber 18 by way of the passage bores 19, and this chamber is connectedwith the shaft bore 25 by way of the transverse bores 26, the samepressure is applied to the valve piston 24 of the pilot valve 20 asdirectly behind the filter sleeve 29 in the spring pressure space 31;this pressure will be referred to as the control pressure in the furtherexplanations. This control pressure engages at the ring surface of thering piston 7 to which this pressure is applied. The resulting pressureforce will be referred to as control pressure force hereinafter. Thespring force of the return spring 6, directed in the same direction asthis control pressure force, furthermore also engages on the ring piston7.

In total, the control pressure force and the spring force form anopening force that engages on the ring piston 7. This opening forcestrives to displace the control slide valve 12, which is rigidlyconnected with the ring piston 7, into the end position on the driveside.

A closing pressure force directed counter to the opening force engagesat the control slide valve 12, which force proceeds from the surface towhich working pressure is applied at the ring piston 7. In thecalculation of the closing pressure force, the surfaces of the ringpiston 7 (and also of the control slide valve 12), to which the workingpressure is applied in “opposite” manner, and the effects of whichcancel one another out as activations at the control slide valve 12, areleft out of account.

FIG. 4 shows the detail Z from FIG. 1 with a schematic representation ofthe control streams of the “closing phase” of the control slide valve12. In this movement direction of the control slide valve 12, referredto as the “closing phase” (represented in FIG. 4 with a directionalarrow R on the control slide valve 12), the control slide valve 12 movesin the direction of the impeller 5 and, in this regard, closes off theoutflow region 10 of the impeller 5 with its outer cylinder 11.

After the pressure has increased to such a point, in connection with theworking play of the ring piston 7 (with the control slide valve 12disposed on it) described in connection with FIG. 3, that the controlslide valve 12 makes contact in its end position on the drive side, theworking pressure necessarily continues to increase with an increasingspeed of rotation of the pump shaft 4 (i.e. with an increasing the speedof rotation of the impeller 5), and could endanger the modules in thecooling system of the internal combustion engine without “regulation ofthe working pressure.”

However, since the control pressure preset by way of the “throttle,” thefilter sleeve 29, continues to also increase as a result of thearrangement according to the invention, with an increasing workingpressure, and this pressure, as has already been explained, is applieddirectly to the valve piston 24 of the pilot valve 20, the pilot valve20 can be pre-adjusted when a maximal permissible working pressure isreached, in such a manner that the valve then opens, and, in thisregard, the cooling medium situated in the pressure chamber 18, isemptied into the suction channel 38, as shown in FIG. 4. In this regard,the laser bores 28 in the “inflow aperture,” the filter sleeve 29, aredesigned/dimensioned, in terms of number and size, in such a manner thatthe amount of coolant that flows In through the filter sleeve 2S is notgreater than can drain away by way of the pilot valve 20.

In this regard, pressure relief takes place in the pressure chamber 18,as well as in the spring pressure space 31 connected with the pressurechamber 18 by way of the passage bore 19, thereby the control pressureforce decreases, and if the spring force remains constant, the openingforce therefore decreases below the value of the closing pressure forcethat is dependent on the respective working pressure, so that theclosing pressure force, which is greater relative to the opening force,now brings about displacement of the ring piston 7 (with the controlslide valve 12 disposed on it) in the direction of the impeller 5. Inthis regard, the control slide valve 12 closes the outflow region 10 ofthe impeller 5 off with its outer cylinder 11, and the working pressuredrops.

When the engine is shut off, the working pressure also drops to “zero,”and thereby both the opening pressure and the closing pressure drop to“zero.”

At this force ratio, only the spring force of the return spring 6engages on the ring piston 7 any longer, and displaces the ring piston 7(with the control slide valve 12 disposed on it) in the end position onthe drive side/pulley side, i.e. into the “fully” open position.

Optimal adjustment of the working pressure, which avoids thedisadvantages of the state of the art, has clear energy advantages, doesnot require any outside energy (such as hydraulics, vacuum, electricalenergy) for pressure or volume stream control, guarantees great failuresafety (fail-safe), and guarantees optimal warm-up of engines at greatengine outputs, with reference to the displacement, which outputsrequire coolant pumps having very large designs, and with which theengine temperature can be adjusted very precisely, even after the enginehas warmed up, during long-term operation, in infinite manner, in highlydynamic manner, and very reliably, over very long periods of use, andwhich simultaneously has a minimal construction size that optimallyutilizes the construction space present in the engine compartment,furthermore can be produced in simple manner, in terms of production andinstallation technology, and in cost-advantageous manner, and whichconstantly guarantees great operational safety and great reliabilityover the entire useful lifetime, results from the interplay of theeffects of the arrangement according to the invention, as explained.

REFERENCE SYMBOL LIST

1 pump housing

2 pump bearing

3 drive wheel

4 pump shaft

5 impeller

6 return spring

7 ring piston

8 rear wall

9 pump interior

10 outflow region

11 outer cylinder

12 control slide valve

13 seal accommodation

14 shaft seal

15 pump mandrel

16 wall disk

17 slide valve guide

18 pressure chamber

19 passage bore

20 pilot valve

21 outlet bore

22 setting screw

23 valve spring

24 valve piston

25 shaft bore

26 transverse bore

27 spring contact

28 laser bore

29 filter sleeve

30 filter piston slide valve

31 spring pressure space

32 control slide valve seal

33 sealing disk

34 impeller rear side space

35 mandrel passage

36 control slide valve interior

37 engine housing

38 suction channel

39 spiral channel

40 pulley

R directional arrow

1: Adjustable coolant pump having a pump housing (1), a pump shaft (4) mounted in/on the pump housing (1) in a pump bearing (2), driven by a drive wheel (3), an impeller (5) disposed in torque-proof manner on a free, flow-side end of this pump shaft (4), having a ring piston (7) spring-loaded by a return spring (6), axially guided in the pump housing (1), on which piston the rear wall (8) of a control slide valve (12) disposed in the pump interior (9) and having an outer cylinder (11) that variably covers the outflow region (10) of the impeller (5) is rigidly attached, wherein a shaft seal (14) is disposed in a seal accommodation (13), between the pump shaft (4) and the pump housing (1), and furthermore, pump mandrels (15) by the pump housing (1) or disposed on the pump housing (1) are disposed in the pump interior (9), on which mandrels a wall disk (16) positioned in a fixed position in the pump interior (9), between the impeller (5) and the rear wall (8) of the control slide valve (12), is disposed, wherein a slide valve guide (17) for the ring piston (7) spring-loaded by the return spring (6) is disposed on the pump housing (1), which guide guides the ring piston (7) on the outer mantle and is at a free distance from the pump shaft (4) with its inner mantle, wherein the slide valve guide (17) lies against the wall disk (16) with its free, flow-side end, so that the components that are adjacent to one another, i.e. the slide valve guide (17), the wall disk (16), a sealing disk (33) disposed on the inner circumference of the disk, spaced apart from the pump shaft (4) by a throttle gap, radially movable on the wall disk (16), the pump shaft (4), and the shaft seal (14) jointly enclose/form a pressure chamber (18) in the form of a ring cylinder, and wherein one/multiple passage bore(s) (19) is/are disposed in the slide valve guide (17), at a distance from the wall disk (16), wherein, a pilot valve (20) comprising a setting screw (22) provided with one/multiple outlet bore(s) (21), a valve spring (23), and a valve piston (24) are disposed in a valve seat bore at the impeller-side free end of the pump shaft (4), in such a manner that the valve piston (24) closes off a shaft bore (25) that is disposed centrally in the pump shaft (4) and, in the closed, state of the pilot valve (20), opens into the pressure chamber (18) by way of one/multiple transverse bore(s) (26) disposed in the pump shaft, wherein the return spring (6), which lies against the ring piston (7) with one spring end, lies against the spring contact (27) of a filter sleeve (29) provided with laser bores (28) with its other spring end, and presses the sleeve against the wall disk (16) in this regard, forming a seal, wherein a filter piston slide valve (30) is rigidly disposed on the ring piston (7), which valve slides along the outside circumference of the filter sleeve (29) when the ring piston (7) is displaced, and wherein the ring piston (7), together with the filter piston slide valve (30), the filter sleeve (29), the wall disk (16), and the slide valve guide (17) enclose a spring pressure space (31) in the form of a ring cylinder, and wherein a control slide valve seal (32) is disposed on the outside circumference of the wall disk (16), i.e. toward the outer cylinder (11), and the sealing disk (33) is disposed on the inside circumference of the wall disk (16), and as a result, an impeller rear side space (34) disposed in the pump interior (9), between the pump shaft (4), the rear wall of the impeller (5), the wall disk (16), and the outer cylinder (11) is separated, on the pressure side, from a control slide valve interior (36) disposed between the rear wall (8), the filter sleeve (29), the wall disk (16), and the outer cylinder (11), wherein the working pressure that is built up in the spiral channel (39) is constantly applied in the control slide valve interior (36), in that mandrel passages (35) are disposed in the rear wall (8). 2: Adjustable coolant pump according to claim 1, wherein the pump housing (1) is flanged onto an engine housing (37), in which the suction channel (38) and the spiral channel (39) are integrated. 3: Adjustable coolant pump according to claim 1, wherein the drive wheel (3) is a pulley (40). 